The invention relates to providing SS7 signalling transport over a high speed network and, more particularly, over an asynchronous transfer mode (ATM) network.
The following acronyms will be used throughout this document:
ATM Asynchronous Transfer Mode
AESA ATM End System Address
CCS Common Channel Signalling
CCSAN Common Channel Signalling ATM Network
DPC Destination Point Code
DS0 Digital Signal, Level 0 (64 kb/s)
DS# Digital Signal, Levelxc3x97(Note: In practice xe2x80x9cDS#xe2x80x9d is used synonymously with xe2x80x9cT#xe2x80x9d, e.g. DS1 and T1)
E1 The European counterpart to T1 (32 channels, 64 kbps per channel, 2.048 Mbps total throughput)
HSLs High Speed Links
ITU International Telecommunication Union
LNP Local Number Portability
Mb/s Megabit-per-second
MSU Message Signalling Unit
MTP Message Transfer Part
MUX Multiplexor/De-Multiplexor
PSTN Public Switched Telephone Network
PVC Permanent Virtual Channel
QoS Quality of Service
SAAL Signalling ATM Adaption Layer protocols
SCPs Service Control Points
SPVC Soft Permanent Virtual Circuit
SSCOP Service Specific Connection Oriented Protocol
SS7 Common Channel Signalling System 7
SSPs Service Switching Points
STPs Signalling Transfer Points
SVC Switched Virtual Circuit
T1 Also known as DS1; 24 DS0 channels at 64 kb/s, and one 8 kb/s synchronisation channel. Total transmission rate is therefore 64 kb/sxc3x9724+8 kb/sxc3x971=1.544 Mb/s.
VCI Virtual Channel Identifier
VCC Virtual Channel Connections
VPI Virtual Path Identifier
A Public Switched Telephone Network (PSTN) is, conventionally, comprised of two networks a voice/data network and a signalling network. The signalling network carries address information for call set-up and tear down. A global standard for telecommunications defined by the International Telecommunication Union (ITU), Telecommnunication Standardisation Sector (ITU-T) for common channel signalling is the Common Channel Signalling System 7 (SS7), a North America version of which has been defined by the American National Standards Institute in T1, the contents of which are hereby incorporated herein; and a corresponding European version of the standard has also been defined by the European Telecommunications Standards Institute.
An SS7 signalling network is made up of different nodes (also referred to as network elements). The nodes include Signalling Transfer Points (STPs), Service Control Points (SCPs) and Service Switching Points (SSPs). These nodes are interconnected by a network of signalling links and together provide a variety of telephony services. For instance, the SS7 network, and its associated protocol, enables, for example: basic call set-up, management and tear down; wireless services; local number portability (LNP); toll-free (800, 888, 877) service; toll (900) service; call forwarding; call display; and three-way calling.
SSPs are switches that originate, terminate or tandem calls. An SSP sends signalling messages to other SSPs to set-up, manage and release voice circuits required to complete a call. An SCP, which provides central database services, may be queried by an SSP to determine how to route a particular call such as, for instance, a toll-free call. An SCP provides to the SSP a response, such as the routing number associated with the toll-free number dialled. This query and response occur over SS7 links. STPs, which also form part of the SS7 network, act as routers to incoming signals received from either an SSP or an SCP. These incoming signals are then routed to the appropriate node based on routing information contained within an SS7 message. Acting as a network hub, an STP improves the operation of the SS7 network by reducing the need for direct links between SSPs.
Currently, most of these SS7 links between nodes are running at speeds of 56 Kb/s or 64 Kb/s. High speed links (based on standards such as GR-2878) are emerging to allow greater bandwidth between the various nodes. However, this bandwidth is often not utilised effectively. Moreover, a fault in the hard-wired connection between nodes results in degradation of the service provided, requires a large amount of manual intervention to rectify, and increases the risk of network failure.
Accordingly, it is desired to provide a system which addresses some of these shortcomings.
The invention provides for multiple virtual channels to be provisioned over a single High Speed Link (HSL) connecting an SS7 node to an Asynchronous Transfer Mode (ATM) network. Each virtual channel on the HSL is dedicated to the transmission of SS7 signalling data between this SS7 node connected to the HSL and another node in communication with the ATM network. A logical connection, which may be, for example, a Permanent Virtual Channel (PVC) or Switched Virtual Circuit (SVC), is provisioned on the ATM network between the SS7 node and the other SS7 node. The invention may provide for direct communication between an SSP and SCP, without the need for an STP intermediary. Further, the invention may provide for a fully associated SS7 network with a reduction in the amount of physical links that would be required in a fully associated conventional SS7 network. The invention may also provide, should a logical connection be configured as an SVC, and relying upon the inherent benefits of an ATM network, for re-routing of SS7 data in the event of a failure of the logical connection.
According to another aspect of the invention, there is provided a method for transmitting SS7 signaling data between a node and an Asynchronous Transfer Mode (xe2x80x9cATMxe2x80x9d) network, the SS7 signaling data destined for a plurality of physical links in communication with the ATM network, the method comprising: for each of the plurality of physical links, establishing a virtual channel over a multiplexing physical link connecting the node and the ATM network; providing an identifier unique to each of the established virtual channels; encapsulating the SS7 signaling data into ATM cells incorporating the identifier corresponding to a destined one of the plurality of physical links; transmitting encapsulated data from the node to the ATM network over the multiplexing physical link on the virtual channel corresponding to the identifier in the encapsulated data.
According to another aspect of the invention, there is provided a method for transmitting SS7 signalling data between a first, a second and a third node over an Asynchronous Transfer Mode (xe2x80x9cATMxe2x80x9d) network, the method comprising: establishing a first physical link between the first node and ATM network; establishing a second physical link between the second node and the ATM network; establishing a third physical link between the third node and the ATM network; provisioning a logical connection on the ATM network between each of the first, the second and the third physical links with the ATM network; provisioning a first virtual channel on the first physical link for the second node; provisioning a second virtual channel on the first physical link for the third node; provisioning a first virtual channel on the second physical link for the first node; provisioning a second virtual channel on the second physical link for the third node; provisioning a first virtual channel on the third physical link for the first node; provisioning a second virtual channel on the third physical link for the second node; transmitting SS7 signalling data from the first node to the second node over the first virtual channel of the first physical link, the logical connection interconnecting the first virtual channel on the first physical link and the first virtual channel on the second physical link over the ATM network; transmitting SS7 signalling data from the first node to the third node over the second virtual channel of the first physical link, the logical connection interconnecting the second virtual channel on the first physical link and the first virtual channel on the third physical link over the ATM network; and transmitting SS7 signalling data from the second node to the third node over the second virtual channel of the second physical link, the logical connection interconnecting the second virtual channel on the second physical link and the second virtual channel on the third physical link over the ATM network.
According to one aspect of the invention, there is provided a device for transmitting and receiving data from a High Speed Link (xe2x80x9cHSLxe2x80x9d), the HSL connecting the device to an Asynchronous Transfer Mode (xe2x80x9cATMxe2x80x9d) network, the device comprising: a first input/output (xe2x80x9cI/Oxe2x80x9d) port in communication with an SS7 first node; a second I/O port in communication with the HSL; a memory in communication with a processor; and the processor is adapted to: receive SS7 signal data from the first I/O port destined for a plurality of SS7 second nodes; generate ATM cells representative of the received SS7 signal data wherein each of the ATM cells generated includes an identifier identifying one of a plurality of channels on the HSL dedicated to transmission of ATM cells between the SS7 first node and one of the plurality of SS7 second nodes; transmit the generated ATM cells through the second I/O port to the HSL; receive ATM cells from the HSL representing SS7 signal data transmitted from the plurality of SS7 second nodes; generate SS7 signal data from the received ATM cells; and transmit the generated SS7 signal data to the SS7 first node.
According to one aspect of the invention, there is provided a method for transmitting SS7 signalling data between a first SS7 node and a second SS7 node, the method comprising: provisioning a first virtual channel on a first physical link between the first SS7 node and an Asynchronous Transfer Mode (xe2x80x9cATMxe2x80x9d) network, the channel dedicated to the signalling data transmitted between the first and the second nodes; provisioning a second virtual channel on a second physical link between the second SS7 node and the ATM network, the channel dedicated to the signalling data transmitted between the first and the second SS7 nodes; provisioning a logical connection in the ATM network between the first physical link and the second physical link; transmitting the SS7 signalling data between the first SS7 node and the second SS7 node on the first channel, the logical connection and the second channel.
According to one aspect of the invention, there is provided a method of transmitting SS7 signaling data between a first SS7 node and a plurality of other SS7 nodes, the method comprising: on a first physical link connecting the first SS7 node to an Asynchronous Transfer Mode (xe2x80x9cATMxe2x80x9d) network, for each pair of SS7 nodes, the pair comprising the first SS7 node and a selected one of the plurality of other SS7 nodes: provisioning a virtual channel on the first physical link, the channel dedicated to the SS7 signalling data transmitted between the first SS7 node and the selected one of the plurality of nodes; provisioning a logical connection over the ATM network between the physical link and the selected one of the plurality of SS7 nodes; encapsulating the SS7 signalling data into ATM cells, the ATM cells incorporating in an ATM header an identifier unique to the channel; and transmitting the encapsulated SS7 signalling data from the first SS7 node to the selected one of the plurality of other SS7 nodes over the channel dedicated to communication between the first SS7 node and the selected one of the plurality of other SS7 nodes and over the logical connection between the first physical link and the selected one of the plurality of other SS7 nodes.
According to one aspect of the invention, there is provided a method of transmitting SS7 data between a plurality of nodes, each of the plurality of nodes in communication with an Asynchronous Transfer Mode (xe2x80x9cATMxe2x80x9d) network, the method comprising: for at least one node of the plurality of nodes, providing for each of the other nodes a virtual channel on a High Speed Link (xe2x80x9cHSLxe2x80x9d), the HSL connecting the at least one node to the ATM network, the virtual channel dedicated to the transmission of data between the at least one node and another of the each of the other nodes; for each of the virtual channels on the HSL, providing a logical connection over the ATM network between the each virtual channel and the each of the other nodes; transmitting data between the at least one node and another of the each of the other nodes over the logical connection on the ATM network and the virtual channel on the HSL, the data comprising ATM cells.
According to one aspect of the invention, there is provided a method of transmitting SS7 data between a first and a second SS7 node, the second node in communication with an Asynchronous Transfer (ATM) network by a first and second physical link, the first node in communication with the ATM network by a first and a second High Speed Link (HSL), the method comprising: provisioning a first virtual channel between the first HSL and the first physical link, the channel dedicated to the SS7 signaling data transmitted between the first SS7 node and the second SS7 node; provisioning a first logical connection over the ATM network between first HSL and the first physical link; provisioning a second virtual channel between the second HSL and the second physical link, the channel dedicated to the SS7 signaling data transmitted between the first SS7 node and the second SS7 node; provisioning a second logical connection over the ATM network between second HSL and the second physical link; encapsulating the SS7 signaling data into ATM cells, the ATM cells incorporating in an ATM header an identifier unique to the channel; and transmitting the encapsulated SS7 signaling data from the first SS7 node to the second SS7 node over at least one of the virtual channels dedicated to communication between the first SS7 node and the second SS7 node and over at least one of the logical connections and over at least one of the first and second physical links.
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.